When does a car battery need to be replaced?

The main function of a car battery is to start your car. Today, most cars have a single maintenance-free 12-volt acid battery (in the photo).Car Battery A car battery is rechargeable. It uses its charge to power the vehicle systems while it's parked and to turn over the engine when you want to start it. Once you start the car, the alternator generates additional electric power to recharge the battery. Read more about recharging below.

Over time, a battery loses its capacity or ability to hold charge. One day, a weak battery will not be able to start your car. Often, this happens when the weather gets cold. When the battery is low on charge, a car will need to be boosted to start. To avoid this situation, a battery should be replaced before its capacity drops to a critical level.

On average, a car battery lasts from 5 to 7 years. The battery lasts longer if the vehicle is driven daily and the battery is kept fully charged. When the vehicle is parked for extended periods of time, the battery deteriorates sooner. We have seen the battery lasts up to 10 years. Several car owners commented on our FB page that their battery lasted for over 11 years.

How can you tell that the battery capacity is getting low? One way is to have it tested. Car Battery Tester The battery capacity is often measured in CCA or Cold Cranking Amps. Many automotive repair shops can test your battery with a special tester (in the photo). The battery tester can measure the actual CCA and compare it to the new battery CCA rating. A battery tester can also test the alternator and the charging system.

The battery and charging system test, known as the AVR test, costs from $20 to $50. Some auto parts stores such as Autozone or O'Reilly Auto Parts offer a battery test at no charge. Many car dealers and repair shops often offer a free battery test as a part of seasonal promotion. After the test, you might get a printout, showing the battery CCA rating and actual CCA. The printout will indicate if the battery should be replaced or just need to be recharged. See the sample printout in the photo.Car Battery Tester
Are there any signs that a car battery is failing? Yes. When the battery is weak, you might notice that the engine turns over slower than usual and the dash lights flicker or go dim when you are starting your car. This happens even if the battery is fully charged after driving.

Another sign is when you operate your power windows after the engine is turned off, the windows move much slower than when the engine is running. You also may notice that the headlights are dim when the engine is idling, but become brighter when the engine is revved. Often you will also see excessive corrosion at the battery terminals and cables when the battery is getting weak.

Can you test a battery with a voltmeter? Battery voltage is a good indicator of the state of charge of the battery.Battery voltage test A fully charged battery should read 12.6 Volt or more. Testing the capacity of the battery with a voltmeter is more difficult. One way is to test the voltage of the battery under the load, for example, with the headlights on. If the battery voltage with engine off and headlights on drops from 12.6 Volt to less than 11 Volt in a couple minutes, the battery is weak.

Can a problem with battery terminals cause the vehicle not to start? Yes. If one of the battery terminals is loose or corroded, it may cause many problems including a no-start, check engine light, stalling, as well as lack of the electric power steering assist.Corroded vs Serviced Battery Terminal Many dealers and reputable repair shops visually inspect the battery terminals during regular oil changes. Your mechanic may recommend servicing battery terminals if they are corroded as in the photo. The battery terminal service costs from $25 to $50. It includes cleaning the battery posts and terminals and applying a protective spray or grease.

How much does the battery replacement cost? A new car battery costs from $60 to $140 and your dealer may charge another $30-$50 to have it replaced. Replacing a car battery as a do-it-yourself project is not very difficult, but the battery is heavy (30-45 lb). Lifting it out of the car can be hard on your back. An old battery is often covered in electrolyte, which is very acidic and can burn your clothes or skin. Here is the DIY battery replacement guide from Pep Boys. Our recommendation is to leave it to the pros.

Where to recycle an old car battery? Some automotive repair shops and car dealers will accept your old battery for recycling. You can find the nearest place to recycle your old battery at Interstate Batteries website.
How long is the battery warranty? In most cars, the battery is covered under the basic bumper-to-bumper warranty. In some cars, the battery coverage is pro-rated. This means, for example, the labor might be fully covered, while the part might be covered 100 percent within the first year, 50 percent within the second year and so on. You can find the warranty coverage details in your Warranty Guide brochure, or on the manufacturer's website.

How to boost a car when the battery is low on charge? To boost a car, you will need a portable booster or jumper cables to boost from another car. Your owners manual has the proper instructions. Car Battery TesterBe careful, if the booster cables are connected to wrong terminals, it may cause a big spark and some fuses and other electrical components could be fried.

How long does it take to recharge a good battery that is low on charge? If the battery is still good, 20-40 minutes of running the engine or driving is usually enough to recharge it. However, be aware that in some cars with electric power steering, the steering assist might not work properly until the battery is sufficiently charged. That can make driving with a low battery dangerous.
If a good battery has not been used for an extended period of time and is completely drained, it might need longer time to recharge.

In some high-mileage cars, the engine may run rough at idle or even stall after replacing the battery. This happens because when the battery is disconnected, all learned settings in the engine computer, including the idle speed are reset. For this reason, some older cars may require the idle speed re-learn after the battery is replaced. The procedure varies for different cars, but it won't take you long to google it. To avoid this problem, many repair shops use a simple memory saving device that keeps the engine computer powered during battery replacement. In modern cars, the idle speed is re-learned as you drive.